The change of insulin levels after six weeks antidepressant use in drug-naïve major depressive patients

Background A reciprocal relationship between diabetes risk and depression has been reported. There are few studies investigating glucose-insulin homeostasis before and after short-term antidepressant treatment in drug-naïve major depressive disorder (MDD) patients. Methods This study included 104 healthy controls and 50 drug-naïve MDD patients diagnosed according to the DSM-IV criteria. These MDD patients were randomly assigned to receive fluoxetine or venlafaxine for six weeks. Depressive symptoms, body mass index, fasting plasma levels of glucose and insulin were measured. Results Compared to the healthy controls, the fasting plasma insulin and the homeostasis model of assessment for pancreatic β-cell secretory function (HOMA-β) was significantly lower in the MDD patients before antidepressant treatment (7.7±4.8 μIU/mL vs. 5.1±4.2 μIU/mL, p=0.006; 114.2±72.3% vs. 74.8±52.0%, p=0.005, respectively). However, these indices were not correlated with depression severity. After 6 weeks of fluoxetine or venlafaxine treatment, the level of HOMA-β borderline significantly increased (108.1±75.5%, p=0.059). Limitations The study was limited by the follow-up duration and lack of a placebo group. Conclusions Antidepressants might affect insulin secretion independently of the therapeutic effects on MDD. Further studies are needed to investigate the long-term effects of antidepressants on insulin regulation in MDD patients.